JPS6241985B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is designed to prevent contamination by adhesion to structures that come into contact with seawater, such as light buoys, buoys for retaining water, floating piers, floating breakwaters, seawater collection pipes for cooling and other uses, discharge pipes, and other seawater passages. Furling,
The present invention relates to a method for preventing fouling of structures by sessile marine organisms that cause fouling, such as sessile marine organisms belonging to tentacles, annelids, arthropods, molluscs, and protochordates. More specifically, the present invention includes a) alkali silicate as a binder, b) activated magnesium oxide having an iodine adsorption amount of 30 to 300 mg/g/MgO on at least the contact surface of a structure that comes into contact with seawater.
15 to 400% by weight based on the amount of SiO ₂ c Total amount of calcium sulfite with b) above b)
+0 to less than 15% by weight based on c) d at least one selected from the group consisting of metallic zinc and inorganic zinc compounds in the above total amount b) +
Applying a coating composition containing 0 to 900% by weight or more of a), b), c), and d) based on c) to prevent adherent marine organisms from adhering to the coated surface. This is a method for preventing fouling of objects that come into contact with seawater. In recent years, with the progress of marine development in coastal waters, the construction and installation of large marine structures, their auxiliary structures, and other similar structures that come into contact with seawater have increased for various purposes. Structures that come into contact with seawater are
In addition to the problem of corrosion caused by seawater, there is also the problem of contamination caused by the growth of adherent marine organisms that cause contamination at or near the contact area, and it is desired to develop an effective method for preventing this problem. For example, navigational buoys, light buoys, mooring buoys, floating piers, floating breakwaters, floating docks, etc., bay and port facility structures, such as mooring ships restaurants and hotels,
Structures that come in contact with seawater, such as moored floating fishing structures and other ledger structures, such as ike structures for fish farming, fixed fishing nets, and similar aquaculture facility structures, are protected against the presence of sessile marine organisms that can cause contamination. By growing attached to structures, they cause damage such as acceleration of corrosion of the structure's base material, inconvenient sinking due to increased weight, and destabilization of balance. In addition, when seawater is used for cooling and other purposes at various facilities, factories, power plants, etc. on the coast, contamination occurs in coastal structures such as seawater collection pipes, discharge pipes, and other waterways and ditches. The resulting adherent marine organisms grow adherently, and in extreme cases, adherently grow on the order of tens of centimeters, reducing the effective area of waterways, increasing flow resistance, clogging screens for removing suspended solids, etc. suffer damage. In order to prevent damage caused by adherent marine organisms that cause contamination to structures that come into contact with seawater,
For example, injection of sodium hypochlorite or chlorinated water, etc. has been carried out, but this inevitably causes troubles of environmental contamination.Currently, coating treatment is carried out with a coating composition containing an antifouling agent. A common method is to cause the elution of an effective concentration of an antifouling agent from a composition to kill or repel adherent marine organisms that cause contamination. For example, ship bottom paints used as antifouling coating compositions include cuprous oxide, tetramethylthiuram sulfide,
Zinc methyl dithiocarbamate, triphenyltin hydroxide, triphenyltin acetate, triphenyltin chloride, etc. are used. However, such antifouling agents have a problem with their toxicity, and organotin compounds and other antifouling agents such as those exemplified above have a negative effect on mice after 24 hours of oral administration.
All of them exhibit fairly high toxicity with an LD ₅₀ of 1000 mg/Kg or less, and their negative effects on other living organisms cannot be ignored, leaving questions about safety and the risk of causing secondary marine pollution. Furthermore, due to the prevention mechanism that prevents contamination by elution of an effective concentration of antifouling agent sufficient to kill or repel adherent marine organisms that cause contamination, it is natural that the secondary contamination mentioned above is prevented. In addition to the disadvantage that troubles are difficult to avoid, there are technical issues such as the fact that it is practically difficult to control the elution rate of the inhibitor, and the sustainability of the antifouling effect because the content of the antifouling agent decreases as it elutes. There is an inherent flaw. Furthermore, since this is a contaminated coating composition used for a structure in contact with seawater, it is required to have adhesion strength to the surface of the structure and seawater resistance that can sufficiently withstand waves and seawater. The present inventor has developed a method that satisfies these requirements and solves the above-mentioned problems and persistence of secondary contamination inherent in conventional compositions with a prevention mechanism that prevents contamination by elution of an antifouling agent. We have been conducting research to develop a new type of antifouling agent that can overcome the problems of poor quality. As a result, it exhibited satisfactory adhesion strength and seawater resistance without containing any contaminants that would cause secondary marine pollution problems. We have also succeeded in developing an inorganic antifouling coating composition that can exhibit significantly superior antifouling effects. According to the research of the present inventor, a) using alkali silicate as a binder and b) adsorbing iodine in an amount of 15 to 500% by weight based on the _amount of SiO2 in a) is 30 to 300%.
Even though the inorganic composition containing active magnesium oxide (mg/g/MgO) as an essential component does not contain any so-called anti-fouling agent, it is still a sticky material that causes pollution. A unique antifouling product that exhibits outstanding antifouling effects against living organisms, as well as satisfactory adhesion strength and excellent seawater resistance to structures that come into contact with or may come into contact with seawater. It has been discovered that the present invention provides a skin covering composition. Although the mechanism of action that produces this unexpected effect is unknown, as will be shown experimentally later with many examples and comparative examples, the antifouling coating composition used in the present invention has excellent water resistance. , seawater resistance,
It has been discovered that this is a new type of non-environmentally polluting antifouling coating composition that has excellent antifouling effects against adherent marine organisms that cause contamination as well as adhesion to substrates and coating workability. . The present inventor has discovered that a) an alkali silicate as a binder, and b) an amount of iodine adsorbed in an amount of 15 to 500% by weight based on the amount of SiO ₂ in a) is 30 to 300%.
mg. The self-curing inorganic composition containing activated magnesium oxide, which is /g. He discovered that it has a composition that exhibits excellent effects in such applications, and proposed Japanese Patent Application Laid-Open No. 57-56364. However, this proposal does not mention at all the antifouling effect against adherent marine organisms that cause contamination, and the inventor himself was completely unaware of such a surprising effect. Therefore, as a matter of course, the present inventor's Japanese Patent Application Laid-Open No. 57-56364
The proposed issue does not contain any disclosures that could suggest such new uses. This time, we have discovered that a composition containing the essential components (a) and (b) and the optional components (c) and/or (d) is effective against adherent marine organisms that contaminate seawater contact structures. On the other hand, it exhibits an outstanding antifouling effect, and even though it does not contain any antifouling agents that can cause secondary pollution, it shows a remarkable and long-lasting antifouling effect and is resistant to waves. It has been discovered that satisfactory adhesion strength withstands seawater resistance. Furthermore, it exhibits particularly excellent antifouling effects against adherent marine organisms belonging to the Mussel family, which are widely distributed in coastal areas around the world and cause pollution, except for particularly low-temperature seawater areas, such as the mussel. It turned out that it would. Accordingly, an object of the present invention is to provide an antifouling method for coating structures that come into contact with seawater or are likely to come into contact with seawater with the above-mentioned antifouling composition. The antifouling coating composition used in the present invention contains the following a) and b) as essential components. a) an alkali silicate as a binder, b) active magnesium oxide with an iodine adsorption amount of 30 to 300 mg/g/MgO in the above a).
15 to 400% by weight based on the amount of _SiO2 Examples of the a) alkali silicate include sodium silicate, potassium silicate, lithium silicate, quaternary ammonium silicate, and mixtures of any two or more of these. I can give an example. The solid content of these alkali silicates can be selected as appropriate, and may be, for example, about 15 to 50% by weight. The above b) activated magnesium oxide is commercially available and can be used in the present invention. The manufacturing method is also known, for example, by pulverizing basic magnesium carbonate, magnesium carbonate, magnesium hydroxide, etc. into particles with a particle size of several 100 microns or less, firing them in a rotary kiln or other suitable firing equipment, and turning the fired composition into a pebble mill, for example. Grind with other suitable grinder, if desired.
The desired active magnesium oxide can be obtained by controlling the particle size by means such as sieving. In the present invention, activated magnesium oxide having an iodine adsorption amount of 30 to 300 mg./g.MgO is selected from among the activated magnesium oxides that can be obtained as described above. If the amount of iodine adsorption is too small outside the above range, the curing effect on component a) tends to be insufficient, and seawater resistance also deteriorates. On the other hand, if the amount of iodine adsorbed is too large outside the above range, a) hardening effect on the component;
In particular, if the curing speed becomes too high, gelation occurs in a very short period of time during mixing, and workability in coating processing becomes extremely poor. Therefore, it is appropriately selected and used within the above range of iodine adsorption amount. b) The amount of active magnesium oxide is from 15 to 400% by weight, preferably from 30 to 300% by weight, based on the amount of _SiO2 in the alkali silicate as binder in a).
It is. If the amount of magnesium oxide (b) is too large outside this amount range, the workability during coating treatment will be poor and it will also cause deterioration of seawater resistance, so the amount is selected within the above range. The antifouling coating composition used in the present invention can further contain c) calcium sulfite.
The amount used is less than 15% by weight based on the total amount b) + c) of b) above, that is, the amount such that b) active magnesium oxide accounts for more than 85% by weight of the main component based on the total amount. Can be used. c) If the amount of calcium sulfite used exceeds the range of 0 to less than 15% by weight based on the above total amount b) + c), for example, when in contact with seawater for a long period of time,
There is a problem with the paint film being chocked.
Furthermore, since the sustainability of the antifouling effect against adherent marine organisms that cause contamination is lost, when using component c), the total amount b) + c) should be 15% by weight.
used in quantities less than c) The combined use of calcium sulfite helps to further improve the adhesion to the base material. Preferably it is available in an amount of 5 to less than 15 weight based on the total amount b)+c). The antifouling composition used in the present invention d) can contain at least one selected from the group consisting of metallic zinc and inorganic zinc compounds. The amount used is from 0 to 900% by weight, preferably from 0 to 300% by weight, based on the above total amount b)+c). Component d) helps improve adhesion to wet substrates such as wet concrete surfaces. However, if the amount exceeds about 900% by weight based on the total amount b) + c), it tends to reduce the seawater resistance of the antifouling composition.
It is used in an amount not exceeding . Examples of inorganic zinc compounds in component d) include zinc oxide, zinc carbonate, and zinc sulfate. The antifouling composition used in the present invention for coating structures that come into contact with seawater or may come into contact with seawater includes the above-mentioned essential components a) and b), as well as optional components c) and/or Besides d) other auxiliary additives can be contained. Such additives include fillers, dispersants,
Colorants, thickeners, antifoaming agents, anti-settling agents, etc. can be mentioned. Specific examples thereof include inorganic or organic powdery or fibrous fillers such as talc, kaolin, calcium carbonate, asbestos, pulp, etc., titanium oxide, chromium oxide, cobalt oxide, white lead, litharge, red iron, Coloring agents such as inorganic pigments such as ultramarine and molybdenum red, and water-dispersible organic pigments such as sodium hexametaphosphate, polyoxyethylene alkyl phenyl ether, naphthalene sulfonic acid condensate, sodium polyacrylate, ammonium polyacrylate, hydroxyethyl cellulose, etc. Examples include thickeners such as polymethylsiloxane, antifoaming agents such as sorbit derivatives, antisettling agents such as bentonite, mica, silica gel, etc. The amount of these additives to be used can be selected as appropriate, but an example of the amount used is about 85% by weight or less based on the weight of the antifouling coating composition. The composition used in the present invention can be formed by mixing the above-described essential components a) and b), optional components c) and/or d), and/or additives. There are no special restrictions on the mixing means, but for example, it is easiest to use a high-speed rotating stirrer for liquid substances, and for powder substances, it is easiest to use a suitable mixer such as a static mixer, ribbon blender, etc. Can be mixed. Using such an antifouling composition, it is possible to provide a method for antifouling a structure that comes into contact with seawater or has the possibility of coming into contact with seawater. Examples of the above-mentioned structures include bays, port facility structures, leisure structures, fishery facility structures, and coastal structures as already exemplified. Examples of base materials constituting the above-mentioned contact portions of structures that come into contact with seawater include concrete, stone, various types of slate, boards made of calcium silicate, inorganic base materials such as pillars and pipes, and aluminum. ,
Examples include metal plates such as iron and stainless steel, metal inorganic base materials such as columns, pipes, and the like. The above-mentioned coating treatment can be performed using any method capable of coating the above-mentioned structure with the composition used in the present invention. For example, spray coating, roller coating, brush coating, or any other known coating method may be utilized. Since the antifouling composition used in the present invention is self-curing at room temperature, it cannot be stored for a long time after being formed into a composition. Therefore, at least the essential components a) and b), as well as c) and/or d), are preferably mixed prior to application at or near the coating site. After coating, you can wait for it to self-cure, but if desired, hot air,
It is also possible to further improve the physical properties and shorten the curing period by heating with infrared rays or other suitable heating means. The coating thickness can be selected as desired, and may be, for example, about 20 μm to about 1 mm. The method of the present invention exhibits an excellent prevention effect in preventing the adhesion of adherent marine organisms that cause pollution. In particular, it can exhibit a remarkable effect in controlling sessile marine organisms belonging to the family Mussel, such as the mussel. Although the antifouling coating composition used in the present invention does not contain any components that correspond to so-called antifouling agents, it exhibits an excellent antifouling effect against adherent marine organisms that cause pollution, and furthermore, it Unlike organic antifouling coating compositions containing leachable antifouling agents consisting of film-forming components, the present invention is a substantially inorganic coating composition and has many advantages. For example, it exhibits an excellent antifouling effect without the trouble of secondary contamination caused by antifouling agents, and exhibits excellent sustainability of this effect. The composition is substantially inorganic, water-soluble and odorless before application and hardening, and has the advantage that dilution, cleaning of painting tools, etc. can be carried out using water, and furthermore, it can be used, for example, under closed conditions. There is no risk of unpleasant odors or generation of flammable or combustible gases even when painting with the paint, and it has excellent work safety and sanitary safety during handling and construction. It has extremely strong adhesion to cement-based substrates such as concrete walls, and maintains sufficient adhesion strength even on wet surfaces without any problems in painting. With ordinary organic paints, it is necessary to sufficiently dry the surface to be painted, and considerable effort is required for surface treatment before painting, but the paint used in the present invention does not require such surface treatment. In this way, the drying operation of the surface to be coated can be omitted, and the application of a primer is also no longer necessary, so that the number of coating operations and the number of times can be reduced, and the construction is extremely easy and the construction period can be shortened. The composition is self-curing at room temperature, and can be easily coated at the construction site to form a cured coating without requiring any particular heat treatment. can be omitted. EXAMPLES Several embodiments of the present invention will be explained in more detail below using Examples along with Comparative Examples. In addition, the test method and evaluation in the following examples are as follows. (1) Water resistance: - The test coating composition was coated on a glass-reinforced cement board (5
×75×150mm), painted to a thickness of approximately 200μm.
Samples cured for 24 hours at ℃ and 60% RH (relative humidity) are tested. After immersing the same sample in water for 720 hours, the surface condition of the paint film was observed with the naked eye.
Assess for blistering and peeling. 1 Chalking Using a chalking tester specified in 5, 17, and 4 of JISK5516, the degree of detached powder adhering to the painted surface of photographic paper is expressed as a score by comparing it with a standard judgment photograph. Score 10 when there is no chalking. The larger the value, the better the stiffening resistance. 2. Blisters Items with no blisters are given 10 points, and graded according to the table below based on the combination of the total area of the blisters and the size of the blisters (average diameter).

[Table] 3 Peeling Items with no peeling are given 10 points, and the grade is determined based on the total area of the peeled parts.

[Table] (2) Seawater resistance: - Test samples prepared in the same manner as described in (1) Water resistance above. After immersing the sample in artificial seawater specified in JISK2510 for 720 hours, it was taken out and the surface condition of the coating film was observed with the naked eye.
Evaluated according to the same coating film evaluation standards of the Japan Paint Inspection Association. (3) Adhesion: - The test coating composition was applied to a 25 x 75 x 75 concrete board with a moisture content of 5% and a moisture content of 80%.
Coat each mm to a thickness of approximately 200μm, and heat at 20℃.
Test samples cured for 24 hours at 60% RH. Place the sample in artificial seawater similar to (2) above.
After being immersed for 240 hours, it was taken out and the adhesive strength (Kg/cm ² ) was measured according to the plane tensile test method specified in JISA6909, and the value is shown. The larger the value, the greater the adhesion. (4) Pot life (coating workability): - After mixing the ingredients to form the coating composition in a constant temperature room at 20℃, measure the runoff time using a JISK5402 paint food cup every 30 minutes. . The pot life (hrs) is the time until it no longer flows out due to the cup. If this time is too short, the coating operation will be unsatisfactory. A desirable pot life is about 1 hour or more. (5) Antifouling property (ability to prevent adhesion to adherent marine organisms): - The test coating composition was applied to a glass reinforced cement board (5 x 1000 x 1000 mm) to a thickness of approximately 200 μm, and the coating was heated at 20°C and 60°C. Test samples cured for 24 hours under %RH conditions. The above sample was immersed for two years approximately 1 m below the sea surface in a natural sea area inhabited by sessile marine organisms (mainly sessile marine organisms belonging to the mussel class, such as mussels), and the unit of sessile marine organisms belonging to the mussel class was determined. The adhered weight per area was measured and expressed as the arithmetic mean value (g/m ² ) of the measured values at three locations. The following tests in Examples and Comparative Examples were conducted at three locations: Osaka Bay, off the coast of Matsuyama, and off the coast of Kurashiki. Examples 1 to 6 and comparative and control examples Each coating composition shown in Table 1 was prepared. The various tests described above were conducted on these coating compositions, and the results are shown in Table 1. In Table 1, the numbers added in brackets to the MgO used indicate the amount of iodine adsorbed. The sodium silicate used was 30% by weight of SiO ₂ and 10% of Na ₂ O.
weight%, solid content is 40% by weight, and potassium silicate is
SiO ₂ 27% by weight, K ₂ O 13% by weight, solid content 40% by weight
It is. Further, in Table 1, the numerical value indicating safety is the LD ₅₀ value of the oral administration acute toxicity test in mice. In Table 1, (b) and (b)〓 are other hardeners Na ₂ SiF ₆ and Al ₃ P ₅ O ₁₀ , which are known as hardeners for alkali silicate.

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Claims (1)

[Scope of Claims] 1. On at least the contact surface of a structure that comes into contact with seawater, a. an alkali silicate as a binder, b. activated magnesium oxide having an iodine adsorption amount of 30 to 300 mg/g.MgO in the above a). of
15-400% by weight based on the amount of SiO ₂ c Total amount of calcium sulfite with b) above b)
+0 to less than 15% by weight based on c) d at least one selected from the group consisting of metallic zinc and inorganic zinc compounds in the above total amount b) +
A coating composition containing 0 to 900% by weight or more of a), b), c), and d) is applied based on c) to prevent adherent marine organisms from adhering to the applied surface. An antifouling method for objects that come in contact with seawater.